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Lecture 04 Linear Structures Sort
Algorithmics (6EAP) MTAT.03.238 Linear structures, sorting, searching, etc Jaak Vilo 2018 Fall Jaak Vilo 1 Big-Oh notation classes Class Informal Intuition Analogy f(n) ∈ ο ( g(n) ) f is dominated by g Strictly below < f(n) ∈ O( g(n) ) Bounded from above Upper bound ≤ f(n) ∈ Θ( g(n) ) Bounded from “equal to” = above and below f(n) ∈ Ω( g(n) ) Bounded from below Lower bound ≥ f(n) ∈ ω( g(n) ) f dominates g Strictly above > Conclusions • Algorithm complexity deals with the behavior in the long-term – worst case -- typical – average case -- quite hard – best case -- bogus, cheating • In practice, long-term sometimes not necessary – E.g. for sorting 20 elements, you dont need fancy algorithms… Linear, sequential, ordered, list … Memory, disk, tape etc – is an ordered sequentially addressed media. Physical ordered list ~ array • Memory /address/ – Garbage collection • Files (character/byte list/lines in text file,…) • Disk – Disk fragmentation Linear data structures: Arrays • Array • Hashed array tree • Bidirectional map • Heightmap • Bit array • Lookup table • Bit field • Matrix • Bitboard • Parallel array • Bitmap • Sorted array • Circular buffer • Sparse array • Control table • Sparse matrix • Image • Iliffe vector • Dynamic array • Variable-length array • Gap buffer Linear data structures: Lists • Doubly linked list • Array list • Xor linked list • Linked list • Zipper • Self-organizing list • Doubly connected edge • Skip list list • Unrolled linked list • Difference list • VList Lists: Array 0 1 size MAX_SIZE-1 3 6 7 5 2 L = int[MAX_SIZE] -
Advanced Data Structures
Advanced Data Structures PETER BRASS City College of New York CAMBRIDGE UNIVERSITY PRESS Cambridge, New York, Melbourne, Madrid, Cape Town, Singapore, São Paulo Cambridge University Press The Edinburgh Building, Cambridge CB2 8RU, UK Published in the United States of America by Cambridge University Press, New York www.cambridge.org Information on this title: www.cambridge.org/9780521880374 © Peter Brass 2008 This publication is in copyright. Subject to statutory exception and to the provision of relevant collective licensing agreements, no reproduction of any part may take place without the written permission of Cambridge University Press. First published in print format 2008 ISBN-13 978-0-511-43685-7 eBook (EBL) ISBN-13 978-0-521-88037-4 hardback Cambridge University Press has no responsibility for the persistence or accuracy of urls for external or third-party internet websites referred to in this publication, and does not guarantee that any content on such websites is, or will remain, accurate or appropriate. Contents Preface page xi 1 Elementary Structures 1 1.1 Stack 1 1.2 Queue 8 1.3 Double-Ended Queue 16 1.4 Dynamical Allocation of Nodes 16 1.5 Shadow Copies of Array-Based Structures 18 2 Search Trees 23 2.1 Two Models of Search Trees 23 2.2 General Properties and Transformations 26 2.3 Height of a Search Tree 29 2.4 Basic Find, Insert, and Delete 31 2.5ReturningfromLeaftoRoot35 2.6 Dealing with Nonunique Keys 37 2.7 Queries for the Keys in an Interval 38 2.8 Building Optimal Search Trees 40 2.9 Converting Trees into Lists 47 2.10 -
Introduction to Algorithms and Data Structures
Introduction to Algorithms and Data Structures Markus Bläser Saarland University Draft—Thursday 22, 2015 and forever Contents 1 Introduction 1 1.1 Binary search . .1 1.2 Machine model . .3 1.3 Asymptotic growth of functions . .5 1.4 Running time analysis . .7 1.4.1 On foot . .7 1.4.2 By solving recurrences . .8 2 Sorting 11 2.1 Selection-sort . 11 2.2 Merge sort . 13 3 More sorting procedures 16 3.1 Heap sort . 16 3.1.1 Heaps . 16 3.1.2 Establishing the Heap property . 18 3.1.3 Building a heap from scratch . 19 3.1.4 Heap sort . 20 3.2 Quick sort . 21 4 Selection problems 23 4.1 Lower bounds . 23 4.1.1 Sorting . 25 4.1.2 Minimum selection . 27 4.2 Upper bounds for selecting the median . 27 5 Elementary data structures 30 5.1 Stacks . 30 5.2 Queues . 31 5.3 Linked lists . 33 6 Binary search trees 36 6.1 Searching . 38 6.2 Minimum and maximum . 39 6.3 Successor and predecessor . 39 6.4 Insertion and deletion . 40 i ii CONTENTS 7 AVL trees 44 7.1 Bounds on the height . 45 7.2 Restoring the AVL tree property . 46 7.2.1 Rotations . 46 7.2.2 Insertion . 46 7.2.3 Deletion . 49 8 Binomial Heaps 52 8.1 Binomial trees . 52 8.2 Binomial heaps . 54 8.3 Operations . 55 8.3.1 Make heap . 55 8.3.2 Minimum . 55 8.3.3 Union . 56 8.3.4 Insert . -
Lecture 6 — February 9, 2017 1 Wrapping up on Hashing
CS 224: Advanced Algorithms Spring 2017 Lecture 6 | February 9, 2017 Prof. Jelani Nelson Scribe: Albert Chalom 1 Wrapping up on hashing Recall from las lecture that we showed that when using hashing with chaining of n items into m C log n bins where m = Θ(n) and hash function h :[ut] ! m that if h is from log log n wise family, then no C log n linked list has size > log log n . 1.1 Using two hash functions Azar, Broder, Karlin, and Upfal '99 [1] then used two hash functions h; g :[u] ! [m] that are fully random. Then ball i is inserted in the least loaded of the 2 bins h(i); g(i), and ties are broken randomly. log log n Theorem: Max load is ≤ log 2 + O(1) with high probability. When using d instead of 2 hash log log n functions we get max load ≤ log d + O(1) with high probability. n 1.2 Breaking n into d slots n V¨ocking '03 [2] then considered breaking our n buckets into d slots, and having d hash functions n h1; h2; :::; hd that hash into their corresponding slot of size d . Then insert(i), loads i in the least loaded of the h(i) bins, and breaks tie by putting i in the left most bin. log log n This improves the performance to Max Load ≤ where 1:618 = φ2 < φ3::: ≤ 2. dφd 1.3 Survey: Mitzenmacher, Richa, Sitaraman [3] Idea: Let Bi denote the number of bins with ≥ i balls. -
Data Structures Binary Trees and Their Balances Heaps Tries B-Trees
Data Structures Tries Separated chains ≡ just linked lists for each bucket. P [one list of size exactly l] = s(1=m)l(1 − 1=m)n−l. Since this is a Note: Strange structure due to finals topics. Will improve later. Compressing dictionary structure in a tree. General tries can grow l P based on the dictionary, and quite fast. Long paths are inefficient, binomial distribution, easily E[chain length] = (lP [len = l]) = α. Binary trees and their balances so we define compressed tries, which are tries with no non-splitting Expected maximum list length vertices. Initialization O(Σl) for uncompressed tries, O(l + Σ) for compressed (we are only making one initialization of a vertex { the X s j AVL trees P [max len(j) ≥ j) ≤ P [len(i) ≥ j] ≤ m (1=m) last one). i j i Vertices contain -1,0,+1 { difference of balances between the left and T:Assuming all l-length sequences come with uniform probability and we have a sampling of size n, E[c − trie size] = log d. j−1 the right subtree. Balance is just the maximum depth of the subtree. k Q (s − k) P = k=0 (1=m)j−1 ≤ s(s=m)j−1=j!: Analysis: prove by induction that for depth k, there are between Fk P:qd ≡ probability trie has depth d. E[c − triesize] = d d(qd − j! k P and 2 vertices in every tree. Since balance only shifts by 1, it's pretty qd+1) = d qd. simple. Calculate opposite event { trie is within depth d − 1. -
Chapter C4: Heaps and Binomial / Fibonacci Heaps
Chapter C4: Heaps and Binomial / Fibonacci Heaps C4.1 Heaps A heap is the standard implementation of a priority queue. A min-heap stores values in nodes of a tree such that heap-order property: for each node, its value is smaller than or equal to its children’s So the minimum is on top. (A max-heap can be defined similarly.) The standard heap uses a binary tree. Specifically, it uses a complete binary tree, which we define here to be a binary tree where each level except the last is full, and in the last level nodes are added left to right. Here is an example: 7 24 19 25 56 68 40 29 31 58 Now, any binary tree can be stored in an array using level numbering. The root is in cell 0, cells 1 and cells 2 are for its children, cells 3 through 6 are for its grandchildren, and so on. Note that this means a nice formula: if a node is in cell x,thenitschildren are in 2x+1 and 2x+2. Such storage can be (very) wasteful for a general binary tree; but the definition of complete binary tree means the standard heap is stored in consecutive cells of the array. C4.2 Heap Operations The idea for insertion is to: Add as last leaf, then bubble up value until heap-order property re-established. Insert(v) add v as next leaf while v<parent(v) { swapElements(v,parent(v)) v=parent(v) } One uses a “hole” to reduce data movement. Here is an example of inserting the value 12: 7 7 24 19 12 19 ) 25 56 68 40 25 24 68 40 29 31 58 12 29 31 58 56 The idea for extractMin is to: Replace with value from last leaf, delete last leaf, and bubble down value until heap-order property re-established. -
Lecture Notes of CSCI5610 Advanced Data Structures
Lecture Notes of CSCI5610 Advanced Data Structures Yufei Tao Department of Computer Science and Engineering Chinese University of Hong Kong July 17, 2020 Contents 1 Course Overview and Computation Models 4 2 The Binary Search Tree and the 2-3 Tree 7 2.1 The binary search tree . .7 2.2 The 2-3 tree . .9 2.3 Remarks . 13 3 Structures for Intervals 15 3.1 The interval tree . 15 3.2 The segment tree . 17 3.3 Remarks . 18 4 Structures for Points 20 4.1 The kd-tree . 20 4.2 A bootstrapping lemma . 22 4.3 The priority search tree . 24 4.4 The range tree . 27 4.5 Another range tree with better query time . 29 4.6 Pointer-machine structures . 30 4.7 Remarks . 31 5 Logarithmic Method and Global Rebuilding 33 5.1 Amortized update cost . 33 5.2 Decomposable problems . 34 5.3 The logarithmic method . 34 5.4 Fully dynamic kd-trees with global rebuilding . 37 5.5 Remarks . 39 6 Weight Balancing 41 6.1 BB[α]-trees . 41 6.2 Insertion . 42 6.3 Deletion . 42 6.4 Amortized analysis . 42 6.5 Dynamization with weight balancing . 43 6.6 Remarks . 44 1 CONTENTS 2 7 Partial Persistence 47 7.1 The potential method . 47 7.2 Partially persistent BST . 48 7.3 General pointer-machine structures . 52 7.4 Remarks . 52 8 Dynamic Perfect Hashing 54 8.1 Two random graph results . 54 8.2 Cuckoo hashing . 55 8.3 Analysis . 58 8.4 Remarks . 59 9 Binomial and Fibonacci Heaps 61 9.1 The binomial heap . -
Problem Set 2 1 Lazy Binomial Heaps (100 Pts)
ICS 621: Analysis of Algorithms Fall 2019 Problem Set 2 Prof. Nodari Sitchinava Due: Friday, September 20, 2019 at the start of class You may discuss the problems with your classmates, however you must write up the solutions on your own and list the names of every person with whom you discussed each problem. 1 Lazy Binomial Heaps (100 pts) Being lazy is nothing to be proud of, but occasionally it can improve the overall execution. In this exercise, we will see how delaying the work of the Union operation in the binomial heap can improve the runtime of several operations of the binomial heap. Delete and Decrease-Key operations in the lazy binomial heap will remain unchanged. To implement the new Union we will store the list of roots as a circular doubly-linked list. That is, every node in the linked list has two pointers left and right, including the head and the tail of the list, such that head:left = tail and tail:right = head: We will also maintain the number of elements stored in the heap as a field Q:n (accessible in O(1) time). Consider the following description of Union(Q1;Q2). It simply appends the root list of Q2 to the right of the root list of Q1: function Union(Q1, Q2) if Q1:head = NIL return Q2 else if Q2:head 6= NIL tail1 Q1:head:left; tail2 Q2:head:left . Pointers to the tails of Q1 and Q2 Q2:head:left tail1; tail1:right Q2:head . Link head of Q2 to the right of the tail of Q1 Q1:head:left tail2 ; tail2:right Q1:head . -
COS 423 Lecture 6 Implicit Heaps Pairing Heaps
COS 423 Lecture 6 Implicit Heaps Pairing Heaps ©Robert E. Tarjan 2011 Heap (priority queue): contains a set of items x, each with a key k(x) from a totally ordered universe, and associated information. We assume no ties in keys. Basic Operations : make-heap : Return a new, empty heap. insert (x, H): Insert x and its info into heap H. delete-min (H): Delete the item of min key from H. Additional Operations : find-min (H): Return the item of minimum key in H. meld (H1, H2): Combine item-disjoint heaps H1 and H2 into one heap, and return it. decrease -key (x, k, H): Replace the key of item x in heap H by k, which is smaller than the current key of x. delete (x, H): Delete item x from heap H. Assumption : Heaps are item-disjoint. A heap is like a dictionary but no access by key; can only retrieve the item of min key: decrease-ke y( x, k, H) and delete (x, H) are given a pointer to the location of x in heap H Applications : Priority-based scheduling and allocation Discrete event simulation Network optimization: Shortest paths, Minimum spanning trees Lower bound from sorting Can sort n numbers by doing n inserts followed by n delete-min’s . Since sorting by binary comparisons takes Ω(nlg n) comparisons, the amortized time for either insert or delete-min must be Ω(lg n). One can modify any heap implementation to reduce the amortized time for insert to O(1) → delete-min takes Ω(lg n) amortized time. -
Part C: Data Structures Wayne Goddard, School of Computing, Clemson University, 2019
Part C: Data Structures Wayne Goddard, School of Computing, Clemson University, 2019 Data Structures 1 C1.1 Basic Collections . 1 C1.2 Stacks and Queues . 1 C1.3 Dictionary . 2 C1.4 Priority Queue . 2 Skip Lists 3 C2.1 Levels . 3 C2.2 Implementation of Insertion . 3 Binary Search Trees 5 C3.1 Binary Search Trees . 5 C3.2 Insertion and Deletion in BST . 5 C3.3 Rotations . 6 C3.4 AVL Trees . 6 Heaps and Binomial / Fibonacci Heaps 9 C4.1 Heaps . 9 C4.2 Heap Operations . 9 C4.3 Binomial Heaps . 11 C4.4 Decrease-Key and Fibonacci Heaps . 12 Hash Tables 14 C5.1 Buckets and Hash Functions . 14 C5.2 Collision Resolution . 14 C5.3 Rehashing . 15 C5.4 Other Applications of Hashing . 16 Disjoint Set Data Structure 17 C6.1 Disjoint Forests . 17 C6.2 Pointer Jumping . 18 Chapter C1: Data Structures An ADT or abstract data type defines a way of interacting with data: it specifies only how the ADT can be used and says nothing about the implementation of the structure. An ADT is conceptually more abstract than a Java interface specification or C++ list of class member function prototypes, and should be expressed in some formal language (such as mathematics). A data structure is a way of storing data that implements certain operations. When choosing a data structure for your ADT, you might consider many issues such as whether the data is static or dynamic, whether the deletion operation is important, whether the data is ordered, etc. C1.1 Basic Collections There are three basic collections. -
Binomal Heaps and Queues Node
EECS 311: Data Structure and Data Management Lecture 21, 22 Binomial Queues Binomial Queues & Heaps Reading: Chapter 6 (except 6.4–6.7); Chap- binomial tree structure: ter 11, Sections 2 and 4. • n is power of 2. • n = 1: binomial tree is a single Binomal Heaps and Queues node. • n =2i two 2i−1 node binomial trees, binary heaps based queues may be improv- make one a child of root of other. able. Example: 1. perform some operations faster? • One node trees: 2. binomial queue 2 . 9 • O(log n) merge. • Two node trees: 3. redundant binomial queue 2 5 • O(1) insert 9 7 • Θ(log n) delete-min, reduce-key. • Four node trees: 4. Fibonacci heaps 2 1 • O(1) insert, reduce-key 9 5 6 3 • O(log n) delete-min 7 8 • Dijkstra’s shortest paths + fi- conacci heap ⇒ Θ(n log n + m). • Eight node tree: Binomial Heaps 1 Def: a binomial heaps is a tree that satis- 6 3 2 fies 8 9 5 heap order: key at node is smaller than keys of children. 7 1 Def: a binomial queue is 1. make k into single-node queue Q′. ′ • a list of binomial heaps. 2. merge Q and Q . • for each i, at most one heap of size 2i. Runtime: merge = Θ(log n) Algorithm: delete-min Algorithm: binomial heap merge Input: Q Input: H1 and H2, two n node binomial i heaps. 1. find heap with min key ⇒ Hi, size 2 ′ • Make tree with greater root-key child of 2. remove heap Hi ⇒ Q root of other tree. -
Page 1 Today's Goals • Mergeable Heaps – Review Binary Heaps
ToDay’s&Goals& • MerGeable&Heaps& – Review&Binary&Heaps& – LinkeD2lists& – Binomial&Trees& – Binomial&Heaps& • ReD2Black& h<p://recursivelyrecursive.wordpress.com/& – Prove&balance& Heaps&O’&Fun& – Look&at&insert&/&Delete& CS&140&HMC&2&Jim&Boerkoel& Binary&heap&representaPons& ExtractMax& 16&&&14&&&10&&&8&&&&&7&&&&&&9&&&&&3&&&&&2&&&&&4&&&&&1& Return&anD&remove&the&larGest&element&in&the&set& 1&&&2&&&&3&&&&4&&&&5&&&&6&&&&7&&&&8&&&&9&&&&10& 16& 16& 14& 10& 14& 10& 8& 7& 9& 3& 8& 7& 9& 3& 2& 4& 1& 2& 4& 1& ExtractMax& ExtractMax& Return&anD&remove&the&larGest&element&in&the&set& Return&anD&remove&the&larGest&element&in&the&set& ?& 1& Heapify- 14& 10& 14& 10& 8& 7& 9& 3& 8& 7& 9& 3& 2& 4& 1& 2& 4& ExtractMax& ExtractMax& Return&anD&remove&the&larGest&element&in&the&set& Return&anD&remove&the&larGest&element&in&the&set& 14& Heapify- 8& 10& 4& 7& 9& 3& 2& 1& MerGeable&Heap& Binary&heaps& A&merGeable&heap&is&any&Data&structure&that&supports&the& followinG&five&operaPons,&in&which&each&element&has&a&key:& • MakeHeap()&2&creates&anD&returns&a&new&heap&containinG&no&elements.& • Insert(H,x)&2&inserts&element&x,&whose&key&has&already&been&filleD&in,&into& heap&H.& • Minimum(H)&2&returns&a&pointer&to&the&element&in&heap&H&whose&key&is& minimum.& • Extract:Min(H)&2&Deletes&the&element&from&heap&H&whose&key&is&minimum,& returninG&a&pointer&to&the&element.& • Union(H1,-H2)-2&creates&anD&returns&a&new&heap&that&contains&all&the& elements&of&heaps&H1&anD&H2.&Heaps&H1&anD&H2&are&“DestroyeD”&by&this& operaPon.& • ALSO:&Increase2Element,&Delete& MerGeable&heaps&